Public scrutiny of crosslinked insulating layer in wire and cable continues to heighten as social consciousness drives the development of ever-more sustainable materials. One favorable sustainability criteria is recyclability. It is well known that crosslinked materials are not readily recyclable and that, at the end of their life, crosslinked materials are generally disposed of by incineration or landfill.
In the search for sustainable substitutes for crosslinked insulating layer with high electrical breakdown strength, it is known that breakdown strength in a polymeric insulation layer is influenced by the polymer morphology. For example, isothermal crystallization of blends of branched polyolefin and linear polyolefin is known to improve the electrical breakdown strength and treeing resistance in polyolefin blends compared to the branched homopolymer for appropriate crystallization conditions.
Isothermal crystallization, however, has shortcomings. Isothermal crystallization requires the target polymer to be held at a constant crystallization temperature for an extended period—sometimes on the order of hours—in order to ensure complete crystallization. For this reason, isothermal crystallization is impractical for many commercial, industrial, and manufacturing applications. For example, an isothermal crystallization procedure for an insulating layer is wholly impractical in wire and cable production.
Accordingly, the art recognizes the need for a substitute to crosslinked insulating layer in wire and cable. Thus, a need exists for a crosslink-free insulating layer with improved dielectric strength and a process for producing same on a commercial scale. A need further exists for an insulating layer that is recyclable.